Kohler engine question

[DanD]

My neighbor has a mower with a 17.5 hp single cylinder vertical crankshaft Kohler Command engine. It is not in a SImplicity tractor, but I thought this may still be of interest to members here anyway. The other day, he started it for just a couple minutes then had to shut it off. Then a few minutes later, he restarted it and when he restarted it, it backfired loudly. Since that time, the engine runs poorly. It seems to labor very hard just to run and after about 20-30 seconds of running, the muffler is so hot it glows bright red. I think it may have sheared the flywheel key when it backfired. The other idea we have is that something fell apart in the muffler and is blocking the exhaust flow. What do you all think? Any other likely answers? The engine is clean and free of debris, full of oil, etc. Thanks in advance.

[BLT]

After a back fire like that, my guess is the flywheel key is partially sheared.

[Brettw]

quote:

---

After a back fire like that, my guess is the flywheel key is patially sheared.

---

I'm on that page too.

[DanD]

Well, here's an update on the engine. I took the flywheel off tonight and took a couple of pictures of what I found. No wonder the engine was running poorly! The local green and yellow dealer told my neighbor that about all that could be wrong with the engine given those symptoms was a fuel problem, but the engine didn't sound like it was starving for fuel to me. Looks like we here were right about the problem. Kohler's list price for the key is about $1.50, so I think my neighbor will be happy. Is the key special material, or is it just an off the shelf woodruff key that one could buy at the hardware store?

[BLT]

While I believe it is a standard woodruff key, I would get the Kohler replacement and you can get (genuine) it a NAPA store if you have one close by. Also for $1.50 you get two per package, switched out a few.;)

[Brettw]

Yup,that would do it. Bought a Regent for $50 with the same issue, that's how I learned. Put 'er all back together and she will run like a champ. Cheapest fix as far as parts go that I can think of too!

[DanD]

Further update: Checked all the small engine /Kohler dealers in town and no one had this key in stock. Napa didn't either but they could get it , but shipping would be like $8 or $10 unless I waited a week for the stock order. Stopped at the John Deere dealer and they had it there in stock in John Deere packaging (not Kohler) for 75 cents. I also ordered a couple of little retainers to hold the grass screen on so it wouldn't come off some day (you basically have to wreck the old ones to get them off and the service manual says to use new) and those will be about $4! Anyway I came home for lunch and installed the flywheel and fired the engine up and it runs great. I've never heard an engine run with the sheared key before. I will always remember that sound now. It was almost painful to listen to. I instructed my neighbor to always have the engine running half throttle when he turns off the key. I think failing to do that caused this problem. Speaking of that, can anyone explain to me why you have to do that on the Kohlers with the electric solenoid on the carburetor to prevent the backfiring? I've never had it explained to me. Seems to me that if the fuel gets shut off when the key goes off, there shouldn't be any fuel or vapors in the engine to cause the problem. I'm just curious because I have gotten myself in the correct habit when shutting off my Sovereign with the 18 hp Command V twin.

[MysTiK]

I thought there was an explanation for the higher throttle shutdown; but can't find anything; did find this in a previous post by RayS. From the CH18 - CH26 horizontal shaft Command owners manual. [url]http://www.kohlerengines.com/onlinecatalog/pdf/2459001_b_808.pdf[/url] page 8.
[img]http://www.simpletractors.com/club2/attach/RayS/fuelshutoffsol.jpg[/img]